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« Previous Version 8 Next » Prompt events:

  • Arrival time of ions at 1 AU suggest a delayed release of the ions relative to the electrons (Wang et al., 2005), is this due to:
    • Different accelerators for electrons and ions or
    • Propagation effects (turbulence, diffusion, magnetic connectivity)?


In X-ray literature "prompt event" is defined as an event where the estimated release time of the electrons that are later seen at 1 AU agrees with the hard X-ray flare peak time within the uncertainty of a few minutes. (YZ: I don't see any difference with the "impulsive" events term used in energetic particles papers, but the correspondence is not 1-1, see below).

Also the spectral shapes of the in situ observed electron spectrum and hard X-ray photo spectrum are statistically correlated. This suggests that a common accelerator produces both the hard X-ray emitting electrons and the escaping electrons (Droege 1996, Krucker et al. 2007). However the observed correlation does not agree with the prediction of the thick-target model (Brown 1971) that would be expected for footpoint emission. This is currently not understood.

Hard X-ray imaging of the solar source region of prompt events



Required observations:

  • SWASWA Normal Mode, several hours, perihelion, other instruments: RPW, MAG, EPD, STIX.
  • MAGMAG Normal Mode
  • SoloHI: Contribute (mode: shock+synoptic), no min. obs time, all distances, w/EUI-STIX-METIS.
  • EUIEUI Synoptic mode (S). EUI FD 174, 304, cadence 10 min. EUI HR 174 and Ly-alpha, cadence 1 min for 30 min before and during X-ray peak.
  • EPD: All sensors: spectra, composition, fluxes, directional information, together with IS instruments. Solar source identification by RS instruments (full disk imaging). Also coordinated multi-s/c SEP observation campaigns with SPP & other missions.


  • METIS: Measurement of coronal outflow velocity and density in corona to identify the shock front. Measurement of shock passage timing relative to the flare occurrence.
    • Products:
      • CME velocity maps 
      • CME density maps 
      • CME directionality
      • CME flag
    • Modes:
      • GLOBAL (before the event, if possible), min. obs time 2 hr, data volume ≤ 300 Mb.
      • CMEOBS, starts after CME flag rise, min. obs time 1 hr (high cadence, 1 min), data volume ~ 2.137 Gb.
      • GLOBAL (after the event), min. obs time 2 hr, data volume ≤ 300 Mb.
    • Other instruments: PHI, EUI, STIX, SoloHI, MAG, SWA, EPD, RPW.


  • Several hours.

Other constraints:

  • Perihelion.
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